Single cell oil production from hydrolysates of alkali pre-treated giant reed: High biomass-to-lipid yields with selected yeasts

Single cell oil (SCO) produced by oleaginous yeasts represents an intriguing source for second generation biofuels or other biobased oleochemicals. This study aimed at improving SCO production from giant reed (Arundo donax L.). Five different yeast species were used to evaluate the lipid yield and fatty acids profile obtained in six media prepared with two enzymatic hydrolysates of mild alkali pre-treated giant reed fibers (washed or not after filtration) and variable nitrogen supplementation (three levels). After pre-treatment and hydrolysis, up to 489 ± 9 mg of reducing sugars per g of initial untreated biomass were obtained. C/N ranged widely (38−258) among the different formulated media, depending on both washing and nitrogen supplementation, and strongly affected SCO accumulation by most of the strains. Lipomyces starkeyi, Rhodosporidiobolus azoricus, and Cutaneotrichosporon oleaginosum reached the highest lipid contents (54–68%) and concentrations (4.8–5.6 g/L). The highest lignocellulosic biomass-to-lipid conversions were obtained with C. oleaginosum, R. azoricus, and L. starkeyi (102 ± 9, 95 ± 9, and 89 ± 3 mg of lipids per g of untreated giant reed biomass, respectively). Oleic, palmitic, linoleic, and stearic acid were predominant in the fatty acids profile, similarly to seed oils. In conclusion, hydrolysates derived from the alkali pre-treated biomass of giant reed are suitable to obtain high lipid yields with selected yeasts, to be used for the biobased industry. •High C/N enzymatic hydrolysates can be obtained from alkali pre-treated giant reed.•Extensive washing of the pre-treated fibers before hydrolysis can be avoided.•Remarkable giant reed-to-lipid yields up to 10% were obtained with oleaginous yeasts.•Highest yields with Rhodosporidiobolus azoricus and Cutaneotrichosporon oleaginosum.•Oleic, palmitic, linoleic, and stearic acid were predominant in the fatty acids profile.